perturbation

"junk DNA" $-mc^2\alpha^2/(2n^2) = -13.6\,\text{eV}/n^2$ $mc^2$ (b) 0.897 (about 90%) 1. Delft (Hensen et al., Nature 526, 682, 2015) 1. Electron lines (solid lines with arrows): 11.1